Apparatus for continuously filtering solids from gases



Dec. 8, 1953 K. KAUTz 2,661,811

APPARATUS FOR CONTINUOUSLY FILTERING SOLIDS FROM GASES Filed Dec. 29, 1951 ATTORNEYS Patented Dec. 8, 1953 UNITED sTATrs esTsNT OFFICE APPARATUS FOR C0N"EEN'UOUSLYy FILTER- ING SOLIDS FROMl GASES KarlKautz, Massillon, Ohio Application December 29, 1951, Serial No. 264,065

(Cl. 18S-60.)

8 Claims. 1

The invention relates generally to apparatus for filtering solid particles from gases, and more particularly to novel apparatus for continuously filtering hot solids from hot gases while flowing Lmder pressure.

Certain prior` filters for separating solid particles from gases have embodied fabric mesh bags on which the solid particles are collected, but such bags are not very durable under shaking or scraping to remove-the solid particles, and arer not able to withstand temperatures much over 20o-225 F. In many instances, it is desirable as well as economical to separate the solids from the gases at much higher temperatures, so that the filtered gases or solids or both can be used Whilehot for various purposes, without the expense of cooling them to a suitableltering temperature and then reheating to a higher operating temperature.

Filters embodying fine metallic screens have been proposed for filtering solids from gases at high temperatures, but such screens are unsatisfactory in many respects. For example, these screens cannot have ne enough porosity for ltering certain solids from gases and still be durable under the expansion and contraction conditions at varying high temperatures. Moreover, the cost of making ne screens of metal which is heat resistant as Well as resistant to oxidation, carburization and dilute acids, is often prohibitive.

It is a general object of the present invention to provide a novel apparatus for continuously filtering solid particles from gases at high temperatures in such manner as to overcome the disadvantages of prior filters.

More particularly, it is an object of the present invention to provide a novel filtering apparatus embodying a lter element of fibrous or comminuted mineral material having high heat resistance.

Another object is to provide a novel filter having mineral material encased in perforate heatresistant metal to permit continuously scraping theltered solid materials frointhe metal surface ofthe filter.

A further Objectis to provide -a novel apparatus including a cylindrical filter with radially adjustable rotatable Scrapers therein.

Another object is to provide iiltering apparatus 2 having a novel filter element which is easily removed for cleaningor replacement.

A further object is to provide a novel cylindrical iilter which comprises a plurality of easily'connected annularsections, making the filter extensible to various lengths.

A` still further object is to provide a novel filtering apparatus which is adapted for continuously filteringV a variety of solid'par-ticles from gases in a variety of materials at greatly varying temperatures up to approximately 1800 F.

These and other objects are accomplished by the parts, elements, materials, combinations and arrangements comprising the present invention, a preferred embodiment of which is shown in the accompanying drawing as exemplifying the best known mode of practicing the invention, a detailed description of the invention being set forth in the following specification, and the scope of the invention being defined in the appended claims.

In general terms, the invention may be stated as comprising a cylindrical tower having refractory wallsand enclosing a cylindrical filtering elementzspaced inwardly'of the Walls, there being'an inletl duct for introducing a mixture of hot solids and gases throughl the Walls into the interior of the iilter and an outlet duct extending through the walls forv taking. off the hot ltered gases from the exterior of the filter, radially adjustable Scrapers revolving Within the filter for scraping solids from the interior thereof, and the lter element being made up of a plurality of separable cylindrical sections each having an inner core of ibrous or comminuted mineral matter enclosed between perforated metallic cylinders.

Referring to the drawing forming part hereof, in which a preferred embodiment of the invention is shown by way of example:

Figure 1 is a vertical cross sectional View of an apparatus embodying myinvention, the central portion, of the tower being broken out;

Fig. 2 is an enlarged fragmentaryy horizontal section through the nite-r element; and

Fig. 3 is a further enlarged vertical section through' the top of the upper filter section.

Similar numerals refer to similar parts throughout the several views of the drawing.

The continuous iilter oi the present invention can be used for ltering solids at ordinary temf perature but is more: particularly adapted for filtering hot solids from hot gases at temperatures up to i600-1800o F. The novel filteringapparatus may be used for filtering various materials to separate hot particles from hot gases, as for example: (a) for filtering hot carbon black from hot thermally-decomposed hydrocarbon gases or from hot combustion gases, (b) for filtering hot reduced metal powders from hot hydrogen or other hot reducing gases, (c) for filtering hot sublimed oxides such as zinc oxide from i hot combustion gases or hot air, (d) for desulfurizing fuel gases by continuously mixing them with sulfur absorbing powdered materials and then continuously filtering, and (e) for filtering out solid particle contaminations from hot gases such as sulfur dioxide or carbon dioxide.

The apparatus for filtering in all of the above examples is essentially the same except for minor modifications which may be required to apply to various uses, and in the interest of brevity and clarity the novel apparatus is shown and described herein as applied to the filtering of hot carbon black from hot thermally decomposed hydrocarbon gases containing principally hydrogen and carbon, so as to separate carbon black from hot hydrogen.

The novel filtering apparatus includes a preferably cylindrical tower indicated generally at I0 having a cylindrical refractory wall il enclosed in a steel casing I2. The wall ll may rest on a circular metal bottom plate I3 which j is supported on posts or columns i4 resting on the fioor or other support, and the plate i3 may be bolted or otherwise secured to flanges i5 at the tops of the columns.

The bottom wall or floor of the tower can be refractory material but is preferably a watercooled hollow metal wall I6 resting on the plate i3 and supported at its outer edge on the posts I4. Inlet and outlet pipes l1 and i8 respectively extend into the bottom wall for circulating cooling water therethrough. The cylindrical wall i l is provided at one side with a refractory lined burn-out flue 2c having a refractory cap 2l nor- A mally closing the same and held in position by .f

a metal cap 22 screwed on the metal sleeve 23 encasing the flue 28.

The top wall 24 of the tower is preferably lined with refractory concrete, and has an outer metal casing 25 with a top plate 26 having stay loops or anchors 2i extending into the concrete. The

metal casing 25 of the top wall preferably has angle flanges 28 attached thereto for detachable connection with similar angle flanges 29 on the top of the side wall casing, the flanges being conu nected by bolts 3Q.

The top wall 24 is provided with an inlet opening 3l which communicates with a refractory flue 32 having a lateral connection 33. The lateral connection 33 is adapted for detachable connection, by means of a drawband 34, with a refractory lined conduit 35 adapted for introducing a hot mixture of gases and solids into the top end of the tower i8, in this case hot hydrogen carrying particles of hot carbon in suspension.

The cylindrical filter element is preferably made up of a plurality of cylindrical sections indicated generally at 3B and positioned end to end as shown in Fig. l. Each section 36 preferably has an annular metal fiange 31 at each end,

" and the flanges of adjoining sections may be welded together at their inner and outer edges to connect the several sections into a rigid cylindrical unit.

As shown in Figs. 2 and 3, each lter section- 36 preferably includes an inner sheet metal foraminous cylinder 3e which is provided with a large plurality of perforations 3S. At intervals circumferentially of the cylinder 38 are reinforcing rods Mi positioned adjacent to or against the radially outer surface of the plate 38 and extending longitudinally or parallel to the axis of the cylinder. The rods are preferably welded at their ends to the annular flanges 37 as indicated at Qi.

The filter sections 3e also include a cylindrical wall or pad 152 normally of substantial thickness around the outside of the rods it composed of fibrous, granular or powdered material. The thickness of the pad 52 may vary from a fraction of an inch to several inches, depending upon conditions required. The material of the pad 42 is heat-resistant mineral matter and allows the pad to adjust itself to the expansion and contraction of the filter cylinder. An outer woven wire screen or mesh is positioned around the outside of the cylindrical pad l2 to hold the material of the pad in place. Preferably, these screens 3 are made in the form of drawbands having flanged ends it which are connected with suitable bolts or clamps so that the drawbands can be drawn together to compress or compact the material of the pad 2 to any desired degree. The drawbands t3, rods il and inner metal cylinder 3S are all of heat resistant metal, as for example Monel metal.

There are various kinds of mineral materials which are suitable for use in the pad d2, and generally these materials may be divided into four classes: (i) asbestos, (2) mineral, rock or glass wool, (3) sand or other granular mineral material, mixed with fibrous material, and (e) powdered mineral material mixed with fibrous material.

More specifically, the common long ber va riety of asbestos known as chrysotile asbestos may be used in the filter pad 42 at moderate temperatures, but because it contains water of crystallization it tends to break down at higher temperatures. Short fiber asbestos known as tremolite or actinolite does not contain water of crystallization and withstands much higher temperatures over long periods, and should be used where conditions require higher temperatures of up to i600-1800u F. Mineral, rock or glass wool can be used for certain applications where the temperature does not exceed the softening point of the wool. For extremely high temperature applications, glass wool made from feldspar or silica glass is very Satisfactory. In certain cases granular or powdered material such as firebrick, may be used if mixed with asbestos or glass wool.

When the cylindrical filter element has been made up by connecting several sections together it is inserted within the tower 1G, the outer diameter-of the cylinder being substantially less than the inner diameter of the tower wall li so that an annular chamber C is provided between the tower wall and the drawbands 53 around the exterior of the filter. A gas conduit Q5 is connected to the lower portion of chamber C for taking off hot filtered hydrogen. Any number of the filter sections 36 may be used depending upon the height of the tower which is calculated to bring the top of the tower wall H close to the top flange V3'! of the top section 36.

In order to make a gas-tight seal at the top of the tower wall and enclose the annular chamber C, an annular stri-p of very light gauge sheet asoman metal de is Welded at its inner edge 'itc the inner edge of the top 4flange Si, and extends radially 'outward therefrom Jbetween the top wall T915 iand the tcp `of the tower 'wall lil lto terminate :between the angle flanges 2d and 12S. The annular strip is very thin and fierib'le so as to readily commodate itself to ldifferences in 'the level oi the filter yand the tower walls and to uneven .surfaces of the tower and top walls. Suitable gaskets may be inserted between vthe top and bottoni surfaces of 'the sealing Astrip '4E and the ang-le Aiianges iZS and 29 to insure a gas-tight seal.

A water-cooled shaft i extends axially 'through the tower Eil, the upper -end project-ing through the removable top wall rd through a suitable stufng gland 58 embodying refractory material iii compressed axially of the shaft 'by a plug '5%. rEhe lower end portion 'of ,the shaft projects through the water-cooled bottom `wall i and bottom plate ES, and has a stufhng gland 5l similar tothe stuing gland d8. The lower projecting end of the shaft il may have a collar 52 welded thereon and supported on a bearing 53 which rests on a concrete support 5d. The `top of the concrete support may have a trough-shaped opening 55 in its upper endpositioned under the bottom end of the shaft to carry Voff the cooling water which enters through the pipe 56 and passes through the hollow shaft si. The bottom end o1" the shaft may have a, stopper '5l therein provided with a stricted opening to control the iiow of the circulating water through the shaft. As shown, the shaft i? may be provided Iadjacent the collar 4i5? with a bevel gear 58 which is driven by a bevel pinion 5s operatively connected 'to suitable driving means for rotating the shaft 4l at a desired speed,

The Scrapers for rotating Within the filter element 3c to scrape carbon blacl; off the inner cylindric surface of the plate 33 are preferably equal in height to the sections 3E, and are staggered or alternately mounted on opposite sides of the shaft, there being preferably one scraper for each lter section 3E. Each scraper may consist of a 'plate or sheet 6@ positioned radially of the filter cylinder with its outer edge closely adiacent to or in contact with the inner surface of the cylinder 33.. Each scraper 6G is preferably mounted on a water-cooled U-shaped hollow bracket iii the inner ends of which are welded to and communicate with the shaft 41 for passing cooling water therethrough, and the scrapers being mounted for sliding radially on the brackets by means of U bolts 62.

In order to make the Scrapers 60 self-adjusting radially, each scraper has a toggle connection with the shaft l? consisting of a preferably double lever arm S3 pivoted to the central portion of the scraper and a lever arm 56 pivoted `to an ear E5 on the shaft. The lever 6d is pivoted to an intermediate portion of the double lever arm 163 ata point located above the pivotal connections with the scraper and the shaft, and the armste and SQ are made of relatively heavy metal stock so that their weight urges the scrapers radially outward. If desired, the Scrapers may be set or locked at any radial position by tightening the U bolt 62 to prevent sliding thereof on the brackets Si. This may be done to allow a coating or layer of the solid material being filtered (in this case carbon) to remain on the inner surface of the filter element, so that the coating will act as a supplementary filtering pad for fresh material.

Opposite the lowermost scraper Bil, a drag scraper B6 preferably of spiral design is attached to :the shaft .411 :for collecting solid material .removed by `the Scrapers 6l) and .dropping :ontnthe bottom Vwall is. The drag scraper 66 gathers the solid material., conveys .it to an .opening '61 :in the bottom Wall ll .adjacent to the Ailter elem-ent and the collected material 'drops 'through the opening '6l into the tapered sleeve 53 :of ia discharge ,drum 59. The tapered sleeve has a screw conveyer 1.0 therein and the sleeve and rconveyer .are rotated by a sprocket 1I 'which seals the outer yend .of the sleeve, the ysprocket being driven by a suitable chain connected'to `a gear motor for .reducing the `speed of rotation of the sprocket. One Aside of the tapered sleeve '68 is provided 'with a port 12 .for intermittently connecting with the opening di, and also is provided rvwith a discharge port 73 for intermittently connecting with :a discharge pipe 14 in the bottom of the drum $9. Thus Whenlthe port 12 is in communication with 'the opening El, the sleeve closes the .discharge pipe i4, and when the port 13 'is kin communication with the disohar-gepipe M'the sleeve closes 'the opening ci.

`The discharge pipe TH empties into a steel drum 15 for collecting the carbon black, and the pipe 14 has an outer sleeve 16 thereon having an annular asbestos pad 11 attached thereto .for making a seal with the top of the drum T5 when the sleeve I6 'is lowered.

In the operation of the novel apparatus for filtering hot carbon black from hot hydrogen, the hot hydrogen containing carbon black particles in suspension is introduced through the conduit 35 into the interior of the filter. The .hot `hydrogen gas and carbon entering through the conduit 35 may be at a temperature of 1'200-1800u F., .having been thermally decomposed from hydrocarbon gas in a suitable furnace and 'then passed through cooling 'means .to reduce the gas and carbon to such temperatures. The continuous filter ofthe present invention can be used in conjunction with `the controlled Yatmosphere furnace disclosed in my co-'pending application, Serial No. 295,280, filed January '10, 1951, when that 'furnace is suitably arranged asa cracking, or hydrogengenerating furnace for thermally decomposing hydrocarbons to yield hot hydrogen and hot carbon black.

After the mixture has filled the inside of the cylindrical filter, the pressure of the incoming gas and carbon will force the hydrogen gas outwardly through the filter element and the carbon particles will be deposited on the inner surface of the metal cylinder 3S, where the built-up particles are constantly scraped off the cylinder by the rotating Scrapers 159. The carbon black removed by the Scrapers drops onto the watercooled bottom wall 1E of the tower where it is cooled and delivered through the drum 59 into the container 15 in the manner previously described. The hot ltered hydrogen at temperatures of about '110D-1700" F. is taken off through the conduit 45 and may be used for various purposes, as for example 4in the-process of smelting hydrogen-reducible ores Idisclosed in my copending .application Serial No. y2dl3'?, filed December 1'1, 195,1.

When the lter pad A2 becomes clogged so that it does not permit the free .passage of `gases therethrough, the carbon particles may be burn-ed out of the filter by closing conduit l5 and introducing hot air through the intake conduit .35 so that it passes through the filter pad and exits through the burn-.out :due 2d. When the nite-r is Aused for filtering from fdiiierent `gases other particles such as `metal or .metallic oxide particles, the nit-er -pad may be cleaned by first lifting out the whole lter cylinder after the top wall 24 is removed, and the lter pad may then be cleaned by leaching or pickling it in suitable dilute acids or alkalis to dissolve the metal particles. Where insoluble solid particles are filtered, the pad 42 of the filter must be replaced when it becomes clogged.

The present improved filtering apparatus provides a filter which is durable at high temperatures, and has an inner perforate metal cylinder which will stand the scraping of the solid particles therefrom. Moreover, the mineral material of the filter pad will withstand the high temperatures and can be compressed to meet varying conditions; The novel cylindrical lter is economical because it is made up of easily connected annular sections which make the filter extensible to various lengths, and the built-up cylindrical filter is easily inserted into the refractory tower or removed therefrom for cleaning or replacing the lter pad. Furthermore, the novel filter has the advantage of being adapted to filter hot solids from a variety of gaseous materials at a wide range of temperatures,

In the foregoing description,` certain terms have been used for brevity, clearness and understanding, but no unnecessary limitations are to be implied therefrom beyond the requirements of the prior art, because such words are used for descriptive purposes herein and are intended to be broadly construed.

Moreover, the embodiment of the improved construction illustrated and described herein is by way of example, and the scope of the present invention is not limited to the exact details of construction.

Having new described the invention, the construction, the operation and use of a preferred embodiment thereof, and the advantageous new and useful results obtained thereby; the new and useful constructions, and reasonable ma chanical equivalents thereof obvious to those skilled in the art, are set forth in the appended claims.

I claim:

l. Filtering apparatus including a tower having refractory walls and a bottom wall, a cylindrical filter spaced inwardly of said refractory walls, means for introducinga het mixture of gases and solids into the interior of the filter, means for removing hot filtered gases from said tower, a rotatable shaft extending axially through said filter, a plurality of vertical radially-adjust able Scrapers staggered on said shaft for scraping hot particles from the inner surface of said filter, and said filter haring a cylindrical core of heat-resistant mineral matter enclosed between inner and outer metal cylinders.

2. Filtering apparatus including a tower hav-v ing refractory walls, a cylindrical filter spaced inwardly of said refractory walls, means for introducing a hot mixture of gases and solids into the interior of the filter, means for removing hot filtered gases from said tower, a rotatable watercooled shaft extending through said filter, a plurality of vertical radially-adjustable scraper staggered on said shaft for scraping hot particles from the inner surface of said lter, a watercooled bottom wall for cooling and `collecting said.

particles, and said lter having a cylindrical core of heat-resistant mineral matter enclosed between inner and outer metal cylinders.

3. Filtering apparatus including a cylindrical tower having a refractory side wall and a removable refractory top wall, a cylindrical filter spaced inwardly of said side wall within said tower and having a foraminous metal cylinder on its inner surface, flexible annular sealing means attached to the top of said cylindrical filter and extending radially outwardly between the side and top walls of the tower, means clamping said sealing means between the top wall and side wall, a duct for introducing a gas containing solid particles into the interior of said filter, and an outlet duct for taking olf filtered gas from between the filter and the tower.

4. Filtering apparatus including a cylindrical tower having a refractory side wall and a removable refractory top wall, a cylindrical filter spaced inwardly of said side wall within said tower and having a foraminous metal cylinder on its inner surface, flexible annular sealing means attached to the top of said cylindrical filter and extending radially outwardly between the side and top walls of the tower, means clamping said sealing means between the top wall and side wall, rotatable Scrapers within said filter for scraping solid particles from said inner metal cylinder, a duct for introducing a gas containing solid particles into the interior of said filter, and an outlet duct for taking off filtered gas from between the filter and the tower.

5. Filtering apparatus including a cylindrical tower having a refractory side wall, a removable refractory top wall and a bottom wall, a cylindrical filter spaced inwardly of said side wall supported on said bottom wall and having a foraminous metal cylinder on its inner surface, flexible annular sealing means attached to the top of said cylindrical filter and extending radially outwardly between the side and top walls of the tower for enclosing and sealing off the annular chamber between the lter and tower side wall, means clamping said sealing means between the top wall and side wall, a duct for introducing a gas containing solid particles into the interior of said filter, a duct for taking off filtered gas from said annular chamber, a rotatable shaft extending axially through said filter, and Scrapers mounted on said shaft for scraping solid particles from said inner metal cylinder of the filter.

6. Filtering apparatus including a cylindrical tower having a refractory side wall, a removable refractory top wall and a bottom wall, a cylindrical filter spaced inwardly of said side wall supported on said bottom wall and having a foraminous metal cylinder on its inner surface, flexible annular sealing means attached to the top of said cylindrical filter and extending radially outwardly between the side and top walls of the tower for enclosing the annular chamber between the filter and tower side wall, means clamping said sealing means between the top wall and side wall, a duct for introducing a, gas containing solid particles into the interior of said lter, a duct for taking off filtered gas from said annular chamber, a rotatable shaft extending axially through said filter, brackets mounted on said shaft and extending radially therefrom, Scrapers slidably mounted on said brackets, and weighted toggle means urging said Scrapers radially outward toward the inner metallic cylinder of the lter.

'7. In apparatus for filtering hot gases from hot solid particles, a cylindrical ltering element made up of cylindrical sections detaohably connected end-to-end, each section comprising an inner perforated metal cylinder having annular flanges at its ends for connecting with adjacent g sections, a core of heat-resistant mineral matter, an outer foraminous metal cylinder compressing said mineral matter and an individual scraper rotatably mounted Within each section for scraping particles from the inner cylinder of each section.

8. In apparatus for filtering hot gases from hot solid particles, a cylindrical filtering element made up of cylindrical sections detachably connected endto-end, each section comprising an inner perforated metal cylinder having annular anges at its ends for connecting with adjacent sections, a core of heat-resistant mineral matter containing iibrous asbestos, an outer foraminous draw band cylinder, and an individual scraper 15 rotatably mounted Within each section for scrap- 10 ing particles from the inner cylinder of each section.

KARL KAUTZ.

References Cited in the le of this patent UNITED STATES PATENTS Number Name Date 1,738,717 Matlock Dec. 10, 1929 l 2,057,446 Rathbun Oct. 13, 1936 0 2,594,456 Kroenlem Apr. 29, 1952 FOREIGN PATENTS Number Country Date 68,445 Switzerland May 8, 1914 663,382 Great Britain Dec. 19, 195] 

